Fouled plugs?

The liquid in ultrasonic cleaners is actually something of a black art! I too have one, mostly for cleaning fuel injectors, and I had to do a lot of research (mostly unsuccessfully) on which liquid to use.
Eventually I was given some advice by a company I use that not only uses ultrasonics for cleaning engine parts but sell the machines too.
That is that there are different chemicals for different purposes/materials and if you use the wrong one you can destroy a component!
They gave me a two-part mixture to try but wouldn’t tell me what it is.

Media blast is the standard.

Otherwise, a good dental pick to pull out the lead deposits (prob none if run LOP) and back in they go !

How do you clean them, @Michael?

Ultranomad wrote:

I have just acquired an ultrasonic cleaner and plan to clean my spark plugs.

I have NEVER heard of anyone using ultrasonic to clean spark plugs.

Rwy20 wrote:

Had to google that, I guess in the US everyone knows that product. :)

Firearm cleaning is not too common in Europe

I have just acquired an ultrasonic cleaner and plan to clean my spark plugs. I am a bit in doubt about the liquid to use, hesitating between water with detergent, a polar organic solvent (e.g. acetone) and a non-polar organic solvent (e.g. kerosene). Does anyone have a qualified opinion?

I would try cleaning it with the usual procedure (~2000rpm and lean to max EGT, with both mags ON) and if that doesn’t do it I would depart and do an airborne mag check soon afterwards.

In the past, two or three times I think, I used to abort and clean the plug. But it’s always the bottom one, so cowlings and spinner have to come off, and my “new policy” has worked every time.

I started doing it after seeing one engineer+pilot do it, and one heavy twin owner I used to know had a bunged-up plug every time and he also just flew with it (I was with him once).

Two caveats however:

• I have an EDM700 so the absence of combustion is totally obvious
• I inspect the whole engine area and especially the ignition harnesses personally at every service
• I inspect the engine from the underside, via the air outlet vents, with a light, before every flight, and all the lower ignition leads are then visible
• I would never depart with a duff magneto half, obviously
• the departure is over land, not over water until the mag check has been done
• the engine started perfectly and nothing else is at all wrong

The airborne mag check requires a special procedure: whenever you switch to one mag or the other one mag, and find a plug is bunged up, close the throttle before switching back to the other mag or to BOTH. Otherwise, you can blow up your exhaust, by igniting unburnt fuel which came out of the non-burning cylinder and is sitting in the cylinder’s exhaust pipe for a few seconds.

As regards using the “air blast” cleaner, AOPA says one thing (do they reference a manufacturer’s instruction?) and Champion says the opposite.

FWIW I almost never clean my plugs other than by manually digging out the lead deposits with a welding nozzle cleaner

The deposits are found only in the lower plugs. Then I swap all the plugs around.

I would never criticise someone choosing to not depart with a fouled plug. I am happy with it personally, because of the above.

Yes Achimba, my habits will evolve.

But WHAT IF, during mag check, one plug is fooled ?
The two times it happened to me (Unison UREM38E), I tried to lean with more power and it worked.
Bosco said he would be much more radical by shutting down and taking the plug out to clean it.
Others opinions ?

PetitCessnaVoyageur wrote:

Leaning during taxing is obviously the best preventive action, but how do you cure if that happens during the mag check ?

Don’t run full rich during runup, just enough to make it to the runup RPM.

STOLman wrote:

Hoppe’s No. 9 cleaner

Had to google that, I guess in the US everyone knows that product. :)